Many electronic devices communicate with each other using wireless local area networks (WLANs), such as those based on a communication protocol that is compatible with an IEEE 802.11 standard (which is sometimes referred to as ‘Wi-Fi’). For example, in some IEEE 802.11 standards, electronic devices communicate with each other using Orthogonal Frequency Division Multiple Access (OFDMA) communication. During the OFDMA communication, resource block subchannels (which are sometimes referred to as ‘resource units’) and associated tones (such as pilot tones and data tones) are used to communicate payloads in frames. Note that a given configuration or arrangement of resource block subchannels and associated tones correspond to a particular bandwidth.
In existing and proposed IEEE 802.11 standards, the bandwidth used by a transmitting electronic device (such as an access point) and the bandwidth used by a receiving electronic device are typically the same. For example, the receiving electronic device may be required to use the same bandwidth as the transmitting electronic device when receiving frames from the transmitting electronic device. However, this constraint can be very limiting. In particular, if the receiving electronic device is allocated a smaller bandwidth than the transmitting electronic device, the receiving electronic device may need to use the bandwidth allocated to the transmitting electronic device in order to receive frames transmitted by the transmitting electronic device, and then may discard the extra additional bandwidth (which is unused). This inefficient approach may be needed because the tones associated with different resource block subchannels (and, thus, with different bandwidths) may be incompatible with each other.
Furthermore, if a receiving electronic device is unable to operate at a larger bandwidth associated with a transmitting electronic device in a WLAN, then the receiving electronic device may be unable to communicate with the transmitting electronic device. This may be frustrating to users of the transmitting electronic device and the receiving electronic device, which may degrade the user experience.
The IEEE 802.11 standards support a variety of channel configurations, including bandwidths of 20, 40, 80, 160 or 80+80 MHz. For wideband operation (e.g., a bandwidth greater than 20 MHz) in a basic service set (BSS), an access point typically selects one of the 20 MHz channels as a primary 20 MHz channel and the remaining channels are secondary (non-primary) 20 MHz channels. For example, for 40 MHz BSS operation, the access point may select a primary 20 MHz channel and a non-primary 20 MHz channel. Moreover, for 80 MHz BSS operation, the access point may select a primary 20 MHz channel and one of the non-primary 20 MHz channels to construct a primary 40 MHz channel, and the remaining non-primary 20 MHz channels may construct a non-primary 40 MHz channel. Similar selections by the access point may be used to construct a primary 80 MHz channel in 160 MHz BSS operation.
During IEEE 802.11 communication, channel access is usually performed via the primary channel using a contention-based channel access technique such as enhanced distributed channel access (EDCA). In particular, before transmitting, an electronic device (or station) may sense the primary channel. Only when the primary channel is free, the electronic device transmits a frame to an access point via at least the primary channel.
Moreover, the electronic device may continue to monitor the primary channel to keep track of the busy/free status of the communication medium. If the electronic device receives a frame from another electronic device on the primary channel, the electronic device may set its network allocation vector based on the duration field in the received frame. Note that the electronic device usually does not decode data that is only communicated on a non-primary channel because the electronic device does not monitor the non-primary channel(s) in existing IEEE 802.11 standards.
Furthermore, as noted previously, transmissions from the electronic device in existing IEEE 802.11 standards typically include the primary channel. An exception is uplink multi-user (UL MU) transmission, which has recently been proposed in the IEEE 802.11ax standard. During UL MU transmission, the access point performs scheduled access and the electronic device is allowed to occupy a portion of the spectrum that does not include the primary channel.
However, the constraint that the communication with the electronic device usually includes the primary channel can be very limiting. In particular, the electronic device may need to use a larger bandwidth than is necessary to convey data, or the electronic device may need to redundantly communicate data in multiple channels and this redundant data may be subsequently discarded. Thus, the lack of flexibility in the channel configuration in the existing or the proposed IEEE 802.11 standards can waste valuable network resources and can increase the power consumption of the electronic device.
In addition, if the electronic device is unable to operate at a larger bandwidth that includes the primary channel, then the electronic device may not be compatible with the existing or the proposed IEEE 802.11 standards and, thus, the electronic device may not be able to communicate with the access point. This may be frustrating to users of the electronic device and the access point, which may degrade the user experience.